Malicious Office (OLE) / .XLSX — malware analysis report

Static analysis result for SHA-256 c5c4be5660bb5735…

MALICIOUS

Office (OLE) / .XLSX

52.5 KB Created: 2015-06-05 18:17:20 Authoring application: Microsoft Excel
MD5: 7cf9d867684f0399b9dd2ca0752176bf SHA-1: b577cef7eeca69f1aad950915ef6242c9aab2163 SHA-256: c5c4be5660bb57356b0ecbc996c077fb980a2898ece1e274cc1849ca69b9029f
160 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File

The sample contains Excel 4.0 macros, specifically an Auto_Open macro, which is a known technique for executing malicious code upon opening the document. The macro uses the RUN function, indicating it attempts to execute an external program. The presence of a lure to enable macros further supports this. The macro appears to construct a URL for downloading a payload, specifically 'http://soberlifeco.com/contra/storage.php', and uses 'rundll32.exe DllRegisterServer' which is often used to execute downloaded DLLs.

Heuristics 4

  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
8509a320b6dbe8e21a7582aae9f5aadecc10d9edb75bf6b48bb45573378d0698
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 2322 bytes